The Muslim pilgrimage to Mecca is known as the Hajj or Hadj. It is an annual Islamic pilgrimage to Mecca, Saudi Arabia, the holiest city for Muslims, and a mandatory religious duty for Muslims that must be carried out at least once in their lifetime by all adult Muslims who are physically and financially capable of undertaking the journey. The Hajj is one of the five pillars of Islam, alongside Shahadah, Salat, Zakat, and Sawm.